Localizing P300 Generators in Visual Target and Distractor Processing: A Combined Event-Related Potential and Functional Magnetic Resonance Imaging Study

Abstract

Constraints from functional magnetic resonance imaging (fMRI) were used to identify the sources of the visual P300 event-related potential (ERP). Healthy subjects performed a visual three-stimulus oddball paradigm with a difficult discrimination task while fMRI and high-density ERP data were acquired in separate sessions. This paradigm allowed us to differentiate the P3b component of the P300, which has been implicated in the detection of rare events in general (target and distractor), from the P3a component, which is mainly evoked by distractor events. The fMRI-constrained source model explained Ͼ99% of the variance of the scalp ERP for both components. The P3b was mainly produced by parietal and inferior temporal areas, whereas frontal areas and the insula contributed mainly to the P3a. This source model reveals that both higher visual and supramodal association areas contribute to the visual P3b and that the P3a has a strong frontal contribution, which is compatible with its more anterior distribution on the scalp. The results point to the involvement of distinct attentional subsystems in target and distractor processing.

Auditory P3a and P3b neural generators in schizophrenia: An adaptive sLORETA P300 localization approach

“…2), including right superior temporal gyrus and bilateral frontal lobe. This finding is in agreement with previous reports (Bledowski et al, 2004;Strobel et al, 2008;Volpe et al, 2007). Prior research has demonstrated that discrimination between standard and non-standard infrequent stimuli reflects frontal lobe activation, sensible to attentional allocation (Goldstein et al, 2002;Polich, 2007;Volpe et al, 2007).…”

“…Symptoms were scored using the Positive and Negative Syndrome Scale (PANSS) (Kay et al, 1987). Socio-demographic and clinical characteristics for both groups are shown in Each EEG recording was off-line re-referenced to the common average (Bledowski et al, 2004) and digitally filtered using a [0.5 40] Hz finite impulse response filter. Then, a three-step artifact rejection method was applied.…”

Neuronal oscillations in the EEG under varying cognitive load: A comparative study between slow waves and faster oscillations

“…Moreover, the OB P300 responses of Figure 5 (c) show a clear P300 subcomponent (termed as the P3b) elicited by the target at the parietal channel Pz, with a significantly higher amplitude and shorter latency for the Easy task condition. This supports earlier works which show that increased task difficulty recruits more sensory and working memory functions, yields longer stimulus evaluation time, and results in amplitude reduction and longer peak latency for the P3b -this subcomponent represents the executive control function, focused attention (Bledowski et al, 2004;Polich, 2007). Increased task difficulty also appears to engage frontal attentional mechanisms more strongly, producing a large frontal/central P300 component (also termed the P3a subcomponent of the P300) when a distracting stimulus interrupts attentional control (Comerchero and Polich, 1998;Hagen et al, 2006).…”

Updating P300: An integrative theory of P3a and P3b

“…As suggested above, variegated P300 data sets can be subsumed by inhibitory modulation in this fashion. Figure 9 illustrates fMRI activation from a three-stimulus oddball task using non-novel distracter stimuli and a difficult target/standard task (Bledowski et al, 2004b). The pattern of fMRI hemodynamic responses indicates that strong frontal lobe activation occurs for distracter stimulus processing, with minimal temporal/parietal activation observed.…”